A gas turbine used in power generation, etc. is composed of a compressor, a combustor, and a turbine as main members. The gas turbine often has a plurality of combustors, and mixes air, which is compressed by the compressor, with a fuel supplied to the combustors, and burns the mixture in each combustor to generate a high temperature combustion gas. This high temperature combustion gas is supplied to the turbine to drive the turbine rotationally.
An example of the combustor of a conventional gas turbine will be described with reference to FIG. 11.
As shown in FIG. 11, a plurality of combustors 10 of the gas turbine are arranged annularly in a combustor casing 11 (only one combustor is shown in FIG. 11). The combustor casing 11 and a gas turbine casing 12 are full of compressed air to form a casing 13. Air, which has been compressed by a compressor, is introduced into this casing 13. The introduced compressed air enters the interior of the combustor 10 through an air inlet 14 provided in an upstream portion of the combustor 10. In the interior of an inner tube 15 of the combustor 10, a fuel supplied from a fuel nozzle 16 and compressed air are mixed and burned. A combustion gas produced by combustion is passed through a transition pipe 17, and supplied toward a turbine room to rotate a turbine rotor.
FIG. 12 is a perspective view showing the fuel nozzle 16, the inner tube 15, and the transition pipe 17 in a separated state. As shown in this drawing, the fuel nozzle 16 has a plurality of premixing fuel nozzles 16a, and one pilot fuel nozzle 16b. A plurality of swirlers 18 are provided in the inner tube 15. The plurality of premixing fuel nozzles 16a penetrate the swirlers 18, and are then inserted into the inner tube 15.
Thus, the fuel injected from the premixing fuel nozzles 16a is premixed with air, which has been converted to a swirl flow by the swirlers 18, and is burned within the inner tube 15.
Patent Document 1: Japanese Unexamined Patent Publication No. 1999-14055
Patent Document 2: Japanese Unexamined Patent Publication No. 2004-12039